Spacecraft are important platforms in space (e.g., earth orbit) for facilitating electronic communications or positioning orbital sensors. In order to maximize their utility, it is often vital to have the ability to control 1) the position of such a spacecraft in space relative to, for example, a heavenly body to which it orbits; and 2) the attitude, or orientation. In particular, without being able to achieve adequate attitude stabilization, at best case the sensors or communication devices cannot function with desired fidelity, and at worst case, instrument systems may become completely inoperable. Therefore, a properly designed attitude control system is important because it often provides mission critical functions such as communications using directional antennas, energy harvesting using solar panels, and instrument pointing.
In the past, attitude stabilization on spacecraft has utilized various technologies including, for example, conventional flywheel mechanisms, control moment gyroscopes, and attitude control thrusters. Such systems have disadvantages including high levels of jitter, degraded performance with time, and a short-life, particularly with the latter technology because the amount of expendable fuel is finite. Magnetic torquers that interact with the Earth's magnetic field have also been used, but such technologies cannot produce sufficiently large torques for fast correction of attitude errors.
It is important to have a means of spacecraft pointing that is highly controllable and accurate as well as one that experiences minimal mechanical wear in order to yield extended life for the system and the spacecraft itself.